Pneumatically-operated liquid slug projector apparatus

ABSTRACT

The liquid slug projector apparatus is entirely pneumatically operated. It comprises a generator having a main housing whose main port fluidly communicates with a liquid body. A first shuttle and a second shuttle are slidably mounted inside the main housing. The first shuttle forms with the main housing a slug chamber for confining therein a liquid slug. A pneumatic source together with a pneumatically-operated valve cyclically cause the shuttles to move relative to or in locked condition with each other, thereby applying during each cycle of operation an abrupt propulsion force to the confined liquid slug which becomes expelled as a very high-velocity liquid jet through the main port.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to water guns for producing in a bodyof water acoustic impulses which are useful, for example, for seismicexploration, and more particularly to such water guns that are operatedexclusively by pneumatic means.

2. Description of the Prior Art

Generators for producing in water acoustic impulses are already known -see for example, U.S. Pat. Nos. 3,369,627, 3,642,090, 3,642,089,3,711,824, 4,131,178, 4,185,714, 4,303,141 and French Pat. Nos.2,307,999 and 2,308,112.

In U.S. Pat. No. 4,303,141 there is already described a liquid slugprojector apparatus which comprises a generator having a housing whosebottom wall defines a main port adapted to be submerged in a liquid bodyfor generating acoustic energy therein. The housing has a single boreforming a larger-diameter bore portion and a smaller-diameter boreportion. First and second shuttles are slidably mounted inside thegenerator's housing. The first shuttle forms with the housing a slugchamber for confining therein a liquid slug. The first shuttle isslidably mounted in the smaller-diameter bore portion, and the secondshuttle is slidably mounted in the larger-diameter bore portion.Hydraulic and pneumatic means are operatively coupled to the generator'shousing to cause the shuttles, during one complete cycle of operation,to move both separately from each other and in locked condition witheach other. During each cycle, the first shuttle applies an abruptpropulsion force to the confined liquid slug which becomes expelled as aliquid jet through the main port in the bottom wall of the housing. Thepneumatic means are adapted for (1) locking and maintaining the firstand second shuttles in a rest position, (2) abruptly releasing the firstshuttle from the second shuttle, and (3) propelling the first shuttletoward the main port in the housing's bottom wall, thereby expelling theliquid slug into the outside liquid body. The hydraulic means areadapted for moving the second shuttle toward the first shuttle.Thereafter, the pneumatic means return the thusly locked first andsecond shuttles to their initial or rest position, thereby completing afull cycle of operation.

It is a main object of the present invention to provide an acousticgenerator which can be operated entirely pneumatically.

SUMMARY OF THE INVENTION

The liquid slug projector apparatus includes a generator having ahousing defining a larger-diameter bore portion, a smaller-diameter boreportion, and a bottom main port adapted to be submerged in a liquid bodyfor generating acoustic energy therein. First and second shuttles areslidably mounted inside the bores of the housing. The first shuttleforms with the main housing a slug chamber for confining therein aliquid slug. The first shuttle is slidably mounted in thesmaller-diameter bore portion, and the second shuttle is slidablymounted in the larger-diameter bore portion. Pneumatic force-producingmeans are provided which include a source of compressed air and anair-operated valve. Both the air source and the valve are directlycoupled to the internal chambers of the generator mostly through airconduits in the second shuttle for pneumatically locking and maintainingthe shuttles in an initial position, for abruptly releasing the firstshuttle from the second shuttle, for propelling the first shuttle towardthe bottom main port, for moving the second shuttle toward and lockingit with the first shuttle, and for returning the thusly locked first andsecond shuttles together to their initial position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view in elevation of a preferred embodiment ofthe acoustic generator; the first shuttle of the generator is shown inits ready-to-be-fired position;

FIG. 2 shows the first shuttle at the very end of its forward stroke, atwhich time a liquid jet becomes ejected at a very high velocity into thesurrounding body of water;

FIG. 3 shows the second shuttle in the process of executing its forwardstroke;

FIG. 4 shows the second shuttle at the very end of its forward stroke,whereat it becomes hooked to the first shuttle;

FIG. 5 shows the hooked first and second shuttles in the process ofexecuting together their return stroke; and

FIG. 6 is an enlarged sectional view of the air-operated valve and itsconnections with the air source and the acoustic generator.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The acoustic apparatus 9 (FIGS. 1-6) of this invention is entirely airoperated. It includes an acoustic generator 10 which produces acousticimpulses within a surrounding liquid body 7 by expelling into the liquidbody a liquid slug 12 at a very high velocity in the form of a liquidjet 8 (FIG. 2) in a downward direction 8a. Generator 10 has acylindrical housing 14 which defines a first smaller-diameter bore 15,and a second, larger-diameter bore 16. Housing 14 has a top stop wall 17and a bottom stop wall 18. Wall 18 defines a main port 19 which, in use,is submerged in the liquid body 7 (FIG. 1), and wall 17 defines a topport 21. Inside bores 15 and 16 are slidably mounted a first shuttle 20and a second shuttle 22.

A pneumatic unit 50 (FIG. 6) together with a 3-way,pneumatically-operated valve 51 cyclically operate on the first andsecond shuttles 20 and 22 to make them move together or relative to eachother, as will be subsequently described.

The first shuttle 20 comprises a first main piston 24 slidably mountedin bore 15 on a seal ring 25, a second piston 26, and an interconnectingpush rod 27.

The second shuttle 22 comprises a third piston 28 defining a port 29, afourth piston 30, and an interconnecting push rod 31 having a centerbore 32. Pistons 26, 28 and 30 are slidably and sealingly mounted insidebores 32, 15 and 16, respectively.

Bore 15 defines a slug chamber 33 between wall 18 and piston 24. A mainreservoir chamber 34 is defined between pistons 28, 30 and housing 14.Wall 18 and piston 28 define piston seats 18a and 28a (FIG. 2),respectively. Seats 18a and 28a have beveled surfaces which match withthe tapered surfaces 24a and 24b, respectively, of piston 24. Wall 18acts as a stop for piston 24 which, in turn, acts as a stop for piston28.

Inside center bore 32 and above piston 26 is formed a trigger chamber35. An internal conduit 36 leading through piston 30 to chamber 35 isconnected to an internal conduit 37 leading through piston 30 to chamber34 through a solenoid-operated valve 40 mounted within the bore of asleeve 22a which extends upwardly from piston 30. Sleeve 22a slidablyand sealingly extends through port 21. An electric line 38 periodicallyapplies control pulses 38a to valve 40. Chamber 34 is directly connectedto pneumatic unit 50 through an external fluid line 42.

A return chamber 49 is formed between piston 30 and top wall 17. Housing14 forms a vent chamber 44 between pistons 24 and 28. Chamber 44 isconnected to the pneumatic valve 51 through an internal conduit 43 whichextends longitudinally through shuttle 22. When chamber 44 is reduced toits smallest volume, as shown in FIGS. 1 and 4-5, it vents to theoutside medium through a normally-closed, mechanically-operated valve 45and an internal, longitudinal vent conduit 46. Valve 45 is mountedwithin piston 28 and has a plunger 47 which is slidably and sealinglydisposed on a valve seat 48.

With particular attention to FIG. 6, the pneumatic unit 50 has an aircompressor 41 which is provided at its output with a pressure regulator39 that is directly connected to reservoir chamber 34 through line 42.

Conduit 43 connects valve 51 with vent chamber 44. Valve 51 has a body23 which defines bores 61, 62 and 56 in which are slidably mountedpistons 71-73, respectively, that form a shuttle 52. Pistons 71 and 72are slidably and sealingly mounted inside bores 61 and 62, while piston73 is slidably but not sealingly mounted inside bore or chamber 56.

Above piston 71 is defined an upper chamber 63, and be1ow piston 72 isdefined a lower chamber 64. Upper chamber 63 is continuously connectedwith the pneumatic unit 50 through an axial bore 66, a diametrical bore65, conduit 58, and line 42. Lower chamber 64 is continuously connectedwith vent chamber 44 through line 43. Chamber 56 is continuouslyconnected with return chamber 49 through conduit 55.

When shuttle 52 is at its lowermost position (FIGS. 1 and 6), its middlepiston 73 sealingly engages a lower seat 53 and is disengaged from anupper seat 54, thereby venting return chamber 49 to the outside mediumthrough conduit 55, chamber 56, and vent tube 57.

When shuttle 52 is at its uppermost position (FIG. 2), piston 73sealingly engages upper seat 54 and is disengaged from lower seat 53,thereby disconnecting return chamber 49 from the outside medium andreconnecting return chamber 49 to the pneumatic unit 50 through conduit55, chamber 56, conduit 58, and line 42. Thus, valve 51 connects returnchamber 49 either with the outside medium through conduits 55 and 57, orwith the pneumatic unit 50 through conduits 55, 58 and line 42.

When vent chamber 44 is reduced to its lowest volume, as shown in FIGS.1, 4 and 5, plunger 47 of valve 45 is lifted from its seat 48 to openvalve 45. Then chamber 44 vents to the outside medium through valve 45and conduit 46, and lower chamber 64 also vents to the outside mediumthrough conduit 43, vent chamber 44, valve 45, and conduit 46. Chamber35 continuously communicates with conduit 46 through a bleed port 35a inthe upper piston 30 (FIG. 2).

To make generator 10 ready for firing, high pressure air is supplied toline 42, conduits 58, 65, 66 and chambers 34 and 63.

Shuttle 52 has sectional dimensions such that the applied pressure willpush it downwardly to its lowermost position, thereby reconnectingreturn chamber 49 with the outside medium 11 through conduit 55, chamber56 and vent tube 57.

BRIEF DESCRIPTION OF OPERATION OF GENERATOR 10

One complete cycle of operation of the acoustic apparatus 9 will now bedescribed with reference to FIGS. 1-5.

The Forward Stroke of First Shuttle 20

In FIG. 1, generator 10 is shown ready to be "fired." In this condition,shuttle 52 of valve 51 is in its lower-most position. High-pressure airis contained in main reservoir chamber 34 and solenoid valve 40 isclosed.

When an electric trigger pulse 38a is transmitted via line 38 (FIG. 2),valve 40 opens for the duration of the pulse to interconnect chambers 34and 35. A downwardly-directed trigger force becomes immediately exertedagainst the upper face of piston 26, thereby breaking the sealingengagement between upper face 24b of piston 24 with seal 28a.

But, when piston 24 becomes disengaged from its seat 28a, thehigh-pressure air in chamber 34 becomes exerted against the entiresurface 24b of piston 24, thereby causing shuttle 20 to become abruptlypropelled downwardly. Also when shuttles 20 and 22 separate from eachother, high-pressure air from chamber 34 fills chamber 44, and plunger47 moves downwardly to close valve 45 and seal off chamber 44. Aftervalve 45 closes, high-pressure air from chamber 34 can no longer vent tothe outside medium.

As shuttle 20 completes its forward stroke, the liquid slug 12 withinchamber 33 becomes expelled at a very high velocity and forms a verycompressed liquid jet 8 to thereby produce acoustic energy within thebody of water 7.

The Forward Stroke of Second Shuttle 22

Normally, valve 40 closes well before the end of the forward stroke ofshuttle 20. Chamber 44 receives high-pressure air from chamber 34 andfeeds it into lower chamber 64 of valve 51 through conduit 43. Becausethe sectional area of piston 72 is larger than the sectional area ofpiston 71, there develops an upper resultant force on shuttle 52 whichmoves it to its uppermost position and causes piston 73 to sealinglyengage upper seat 54. Conduit 55 and chamber 56 become disconnected fromvent tube 57. As a result, return chamber 49 also becomes disconnectedfrom the outside body of water 7 and becomes reconnected to thepneumatic unit 50 through conduit 55, chamber 56, conduit 58, and line42.

High-pressure air from compressor 41 starts pressurizing return chamber49. The sectional areas of the second shuttle 22 are such that when thepressures within chambers 34, 44 and 49 become stabilized, theredevelops a downward resultant force on the second shuttle 22 (FIG. 3).As a consequence, the second shuttle 22 is pushed toward and becomeshooked to the first shuttle 20 thereby opening valve 45 (FIG. 4). Whenseal 28a becomes compressed by tapered surface 24b of piston 24, chamber44 is completely vented to the outside medium through open valve 45 andconduit 46. At the same time chamber 35 continues to slowly bleed offair pressure to the outside medium through bleed port 35a in piston 30.

The Return Stroke of Locked Shuttles 20 and 22

With valve 40 closed, main reservoir chamber 34 is pressurized throughline 42; with valve 45 open, vent chamber 44 and lower chamber 64 ofvalve 51 vent through conduit 46 to the outside medium, thereby allowingshuttle 52 to move to its lowermost position, whereat return chamber 49becomes disconnected from pneumatic unit 50 and becomes reconnected tothe outside medium.

High-pressure air contained in return chamber 49 will vent to theoutside. When chamber 49 is sufficiently vented, the hooked togetherfirst and second shuttles 20 and 22 return to their uppermost position(FIG. 5), due to the difference in the surface areas of pistons 28 and30. Generator 10 is now ready to start the next cycle of operation.

In sum, the source of compressed air 41 and the pneumatically-operatedvalve 51 are connected to generator 10, whereby compressor 41continuously feeds compressed air into the main reservoir chamber 34.

The normally-closed, electrically-operated valve 40 is connected betweenthe reservoir chamber 34 and the trigger chamber 35. When energized,valve 40 causes pressurized air from the reservoir chamber 34 to flowinto the trigger chamber 35, thereby abruptly propelling the firstshuttle 20 leading it to execute a forward stroke which expels theliquid slug 12 in the form of a liquid jet 8.

The pneumatically-operated valve 51 supplies compressed air fromcompressor 41 to return chamber 49 to cause the second shuttle 22 tomove toward and lock with the first shuttle 20, thereby recompressingthe air in reservoir chamber 34. The recompressed air in chamber 34causes the locked shuttles 20, 22 to return to their initial position,thereby completing one cycle of operation.

What is claimed is:
 1. A liquid slug projector apparatus, comprising:agenerator having a housing including a first bore having a bottom stopwall defining a main port; a second bore having a top stop wall defininga top port; a first shuttle having a first piston, a second piston, anda push rod interconnecting said first and second pistons; a secondshuttle having a third piston, a fourth piston, and an interconnectingpush rod defining a third bore therein; said first piston being slidablymounted in said first bore; said second piston being slidably mounted insaid third bore; said third piston being slidably mounted in said firstbore; said fourth piston being slidably mounted in said second bore;said second shuttle having a sleeve which slidably and sealingly extendsfrom said fourth piston through said top port; said first bore defininga slug chamber for containing a liquid slug between said bottom stopwall and said first piston; said second bore defining a return chamberbetween said fourth piston and said top stop wall; said third boredefining with said second piston a trigger chamber; a vent chamberformed between said first and third pistons; a main reservoir chamberformed between said first and second shuttles and having a first inlet;an air-operated valve having a second inlet and a valve element havingtwo operative positions; said first and second inlets being adapted tocontinuously receive compressed air from a single air line; saidcompressed air maintaining said shuttles in a rest position and thenabruptly releasing said first shuttle from said second shuttle, therebyabruptly expelling said confined liquid slug at a very high-velocitythrough said main port into said liquid body; said valve element in oneoperative position supplying compressed air from said air line to saidreturn chamber to cause said second shuttle to move toward and lock withsaid first shuttle; and said valve element in another operative positionventing said return chamber to the outside medium thereby causing saidlocked shuttles to return to their rest position.
 2. The apparatus ofclaim 1, anda normally-closed, electrically-operated valve connectedbetween said reservoir chamber and said trigger chamber; and saidelectric valve when energized causing pressurized air from saidreservoir chamber to flow into said trigger chamber, thereby abruptlydownwardly propelling said first shuttle from its rest position toexecute a forward stroke which expels said liquid slug at a very highvelocity through said main port into said liquid body.
 3. The apparatusof claim 2, whereinsaid air-operated, valve is a 3-way valve directlyand rigidly connected to said return chamber.
 4. The apparatus asclaimed in claim 3, wherein:said valve element is operated by the airpressure in said vent chamber and supplies compressed air from said airline to said return chamber when said vent chamber is under highpressure; and said valve element venting said return chamber to saidoutside medium when said vent chamber is itself being vented to saidoutside medium.
 5. The apparatus of claim 4, whereinsaid air-operatedvalve is connected to said vent chamber through an air conduit having afirst rigid part defined by said second shuttle, and through a secondflexible part flexibly connecting said first rigid part to saidair-operated valve.
 6. The apparatus according to claims 1, whereinsaidair-operated valve having a body and a third shuttle; said body definingfirst, second, and third bores in which are slidably mounted first,second, and third pistons of said third shuttle; said first and secondpistons being slidably and sealingly mounted inside said first andsecond bores, and said third piston being slidably but not sealinglymounted inside said third bore; an upper chamber situated in said bodyabove said first piston, and a lower chamber situated below said secondpiston; said upper chamber being continuously connected to said air linethrough bores in said third shuttle; said lower chamber beingcontinuously connected to said vent chamber; and said third bore beingcontinuously connected to said return chamber.
 7. The apparatus of claim1, wherein:said valve element is responsive to the air pressure in saidvent chamber to supply compressed air to said return chamber when saidvent chamber is under high pressure; and said valve element venting saidreturn chamber to said outside medium when said vent chamber is itselfbeing vented to said outside medium.
 8. The apparatus of claim 7,whereinsaid 3-way valve has a control chamber which is connected to saidvent chamber through a rigid air conduit defined by said second shuttle;and a flexible air conduit flexibly connecting said rigid conduit tosaid control chamber.